Project Summary HIV-uninfected pregnant and breastfeeding women in South Africa are at high risk of HIV acquisition despite increased uptake of antiretroviral therapy (ART) and maternal seroconversion during pregnancy and breastfeeding contributes significantly toward pediatric HIV infections. Comprehensive HIV prevention programs that include biomedical interventions, such as pre-exposure prophylaxis (PrEP), could dramatically reduce HIV incidence in pregnant and breastfeeding women in high HIV incidence areas and reduce vertical HIV transmission. The overarching goal of this proposal is to evaluate the feasibility and acceptability of integrating PrEP into antenatal and postnatal care, to describe the cascade in women initiating PrEP in this setting, and to evaluate the reasons for attrition along the PrEP cascade in a cohort of pregnant and breastfeeding women Candidate: I am an HIV epidemiologist with a background in HIV research and program development, implementation in Africa. I am applying for a five-year Fogarty IRSDA K01 award to obtain training, mentorship, and research experience to become an independent investigator capable of obtaining R01 funding. Mentoring: I have put together an exceptional multi-disciplinary mentoring team with extensive experience in HIV prevention research in South Africa that integrates clinical research, epidemiology, PrEP and qualitative methods. Drs. Thomas Coates (UCLA) and Landon Myer (University of Cape Town, South Africa) will serve as co-Primary mentors and bring complementary expertise in behavioral science and clinical trials. In addition to my two Primary mentors, my co-mentors provide expertise in specific content areas and methodologies and are based in both the U.S. and South Africa. My co-mentorship team includes: Dr. Pamina Gorbach (U.S.-based, behavioural epidemiologist with significant experience in mixed methods research, Dr. Linda-Gail Bekker (SA-based, clinical trials, PrEP and research in young women). Training: Specific training in clinical trials, advanced biostatistics, behavioural science and mixed methods analysis, will be achieved through intensive mentored training, coursework, workshops and and primary research in South Africa. Guided by my mentorship team, these training and research experiences will establish my independent investigator career as an expert in research in pregnant and breastfeeding women in low resource settings. Research: The specific aims are to: (1) Evaluate the feasibility and acceptability of integrating PrEP into antenatal and postnatal/well-baby services; (2) Describe the PrEP cascade of initiation, retention, and adherence in a cohort of HIV-uninfected pregnant and breastfeeding women, (3) Evaluate attrition and associated factors across the PrEP cascade. The results from our study will provide a model to implement WHO guidance and scale-up PrEP delivery in pregnant and breastfeeding women at risk of HIV and contribute to the elimination of vertical HIV transmission. We will use the formative research to apply for a R01 grant to evaluate interventions to improve retention in the PrEP cascade in a larger cohort of pregnant and breastfeeding women.